Microchannel system for rate-controlled, sequential, and pH-responsive drug delivery

Controlled delivery of drug at a constant rate, in a sequential order, or responsive to environment conditions has been pursued for a long time to enhance the efficacy of therapeutic molecules and to minimize side effects of highly potent drugs. However, achieving such delicately-controlled delivery of a drug molecule is non-trivial and still remains a challenge. We propose the use of microchannels to control the rate, sequence, and pH-responsiveness of drug delivery for high precision and predictability. In this study, we introduce elementary drug delivery units consisting of micro-reservoirs and microchannels that have variations in their lengths, widths, numbers, and straightness. The release study demonstrates that the release rates of model drugs can be modulated by the design of microchannels. Finite element modeling of drug release predicts the performance of the drug delivery units with high accuracy. The possibility of sequential drug delivery is also demonstrated using biodegradable polymer plug in microchannels. Finally, pH-responsive delivery of drugs in microfluidic units is also discussed and demonstrated via cell viability tests.(c) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.